Brain Encyclopedia

Learn the key terms used in Neuroscience and expand your knowledge of the brain.


  • Acetylcholine (ACh)

    A neurotransmitter that plays a large role in cognition and in motor activity. It is found in the central and in the peripheral nervous system. Some of the medications commonly used to treat early cognitive symptoms of Alzheimer's disease and other dementias target ACh.

  • Action Potential

    An electrical potential that spreads across the neuron membrane. The action potential travels down the axon as voltage sensitive sodium channels open. Action potentials are the main mechanism of information exchange between neurons.

  • Activation and Arousal

    These are broad terms referring to the mechanisms of keeping the brain in the states of optimal functional readiness. They are mediated mostly by the brain stem and the thalamus.

  • Afferent Nerves

    Afferent or sensory nerves (pathways) relay incoming information from sensory receptors to the central nervous system.

  • Aging

    The process of becoming older. This can be used to refer to development, deterioration, and maturation.

  • Alexander Luria

    Alexander Romanovich Luria (1902-1977) was one of the most important psychologists of the 20th century. He is credited with being a founding father of neuropsychology, and has also made significant contributions to cross-cultural and developmental psychology.

  • Allele

    One variation of a specific gene.

  • Alzheimer's Disease (AD)

    A degenerative brain disorder characterized by gradually worsening cognitive impairment, which may affect memory, language, decision making, and other functions. AD is usually diagnosed in people in the sixties and older, but earlier onset is also possible. AD is the most prevalent form of dementia.

  • Amygdala

    The name means "almond" in Greek. It refers to the shape of a brain structure located on the inside of temporal lobe. The amygdala is important in emotional regulation, the evaluation of stimuli, and fear conditioning.

  • Anterior

    Refers to structures located in the front or front end of the brain.

  • Anterior Cingulate Cortex

    A part of the brain that is thought to regulate the anticipation of reward, empathy, decision making, as well as elements of emotion and other cognitive functions. It is often classified as the part of the frontal lobe.

  • Attention

    An important cognitive function allowing the individual to focus on certain incoming information or on a cognitive activity. It is common to distinguish between voluntary attention driven by internally formulated goals; and automatic attention driven by external sensory stimuli. Some of our games that target attention are Ribbit Racers, Bag Snag, and Juice It.

  • Attention-Deficit/Hyperactivity Disorder (ADHD)

    A developmental disorder characterized by inattention, impulsivity, and hyperactivity, affecting mostly voluntary attention. The term ADHD is often used by the general public loosely to refer to any cognitive impairment. Concern has been expressed by some neuroscientists that ADHD is commonly over-diagnosed.

  • Auditory Processing

    Processing acoustic information received through the ears.

  • Autism

    A neurodevelopmental condition characterized by poor verbal and social skills and cognitive rigidity. Autism is a syndrome rather than a single disorder and may have a number of different underlying causes.

  • Autonomic Nervous System

    A division of the peripheral nervous system that receives information from and acts upon the internal organs. This system controls the "fight or flight" and "rest and digest" responses to the environment.

  • Axon

    A long, protruding part of a neuron allowing it to make contact with other neurons. The action potential is transmitted along the axon.

  • Axon Terminal

    The end of an axon, which contains synaptic vesicles filled with neurotransmitter molecules.


  • Basal Ganglia

    This term refers to several functionally diverse subcortical brain structures including the caudate nucleus, putamen, globus pallidus, substantia nigra, and subthalamic nuclei. The amygdala is sometimes classified as part of the basal ganglia.

  • Brain Stem

    This part of the brain developed early in evolution. It contains multiple nuclei and serves multiple functions related to sensory processes, motor processes, arousal, as well as the basic vital functions. Note: The image below above shows the brain stem in addition to the diencephalon, which is part of the forebrain.


  • Caudate Nucleus

    The caudate nucleus is part of the basal ganglia and plays a role in initiating and gating various behaviors. The caudate nucleus and the putamen are referred to as the striatum .

  • Central Nervous System

    The brain and the spinal cord.

  • Cerebellum

    The area of the brain that controls motor coordinator and sensory information, as well as correcting muscle movements and promoting equilibrium. More recent studies suggest that the cerebellum also plays a role in higher-order functions such as decision making .

  • Cerebral Cortex

    The outermost sheet of the brain characterized by multilayered organization. It is common to distinguish between the "new" cortex (the neocortex) and the "old" cortex (paleo- and archicortex). The cerebral cortex is responsible for most complex forms of cognition, including language, memory, decision making, and others.

  • Cerebrovascular Accident (CVA)

    The technical term used for a stroke that encompasses several different vascular disorders that may result in brain damage. It is common to distinguish between the more common ischemic CVA, when a vessel is occluded and results in blood supply deprivation of a certain brain region, and the less common hemorrhagic CVA, when the blood vessel is ruptured and blood spills into a certain brain region.

  • Cognition

    A very general term that refers to various complex mental processes, such as language, perception, memory, attention, decision making, problem solving, and others.

  • Cognitive Deficits

    A very broad term referring to problems with memory, attention,language,spatial processing, decision making or any other higher-order mental function.

  • Cognitive Exercises

    Mental tasks designed to challenge specific cognitive functions.

  • Cognitive Neuroscience

    A rapidly developing discipline concerned with the studies of the brain mechanisms of cognition using advanced neuroimaging and computational methods.

  • Cognitive Novelty

    Cognitive challenges which cannot be addressed with previously acquired knowledge or skills.The best game to challenge cognitive novelty skills is Odd Man Out.

  • Communication Disorder

    A very broad term referring to problems with the ability to effectively exchange information with other people through the means of language.

  • Corpus Callosum

    A large bundle of fibers connecting the two cerebral hemispheres and enabling communication between them.

  • Cortical Organization

    Principles which capture the way various functions are represented in the cortex.

  • Cortico-Subcortical Interactions

    The cortex in interconnected with virtually every subcortical structure both anatomically and functionally. No brain structure functions in isolation from other brain structures, and there is a constant, ongoing interplay between them.

  • Crystallized Intelligence

    This term refers to a set of highly entrenched cognitive skills and knowledge.


  • Decision Making

    An element of cognition decision making is a complex mental process by which various options in attaining a goal are formulated and selected.

  • Dementia

    A disorder characterized by gradual decline of cognitive functions usually associated with aging. Several forms of dementia exist, including Alzheimer's Disease, Lewy Body Disease, Fronto-Temporal Dementia and others.

  • Dendrite

    The part of a neuron that receives signals from other neurons, thus permitting information exchange between neurons.

  • Dendritic Spines

    Knoblike formations on dendrites which receive electrochemical communications from axon terminals of other neurons via the synaptic cleft.

  • Depression

    A disorder characterized by dulled, sad, or down mood, often accompanied by diminished pleasure or interest in activities. Cognitive impairment is often present in depression.

  • Disengage Attention

    Withdrawal of attentional focus from a particular stimulus.

  • Distributed/Divided Attention

    Rationing attentional resources between several cognitive activities occurring in parallel. The best games to challenge distributed and divided attention are Bag Snag and Balloon Bust.

  • Dopamine (DA)

    A neurotransmitter that plays a role in cognitive processes such as decision making and working memory, rewards, and motor behavior.

  • Dorsal

    Toward the back when referring to the spinal cord and the brain stem. Towards the top when referring to the cortex and the forebrain.

  • Dorsolateral Prefrontal Cortex (DLPFC)

    The subdivision of the frontal lobes important in executive functions" such as planning

  • Dyslexia

    A disorder of reading due to the impairment of one or more of the core skills of reading such as awareness of word sound structure, letter identification, and the application of knowledge dealing with letter-sound relationships. The disorder can be developmental or acquired. Most cases of dyslexia are secondary to spoken language deficits.


  • Episodic Memory

    Memory for specific events which are encoded with reference to the circumstances of their acquisition. The best games to challenge episodic memory are Shopkeeper and Match Maker.

  • Executive Function Disorder

    A broad term referring to the deficit of planning, impulse control, mental flexibility, judgment, or other functions mediated by the frontal lobes. See also Executive Functions.

  • Executive Functions

    Functions that regulate and supervise cognitive operations and behavior mediated by the frontal lobes. They include planning, working memory, distribution of attention, mental flexibility, impulse control and others. The best game to challenge executive functioning is Ribbit Racers.

  • Explicit Memory

    Memory that can be consciously recalled and communicated. The best games to challenge explicit memory are Shopkeeper and Match Maker.


  • Fluid Intelligence

    The ability to solve novel problems or work with new ideas.

  • Focus/Executive Attention

    A process of concentration that governs isolating an important stimulus from other stimuli in the sensory world.

  • Focused Attention

    A form of selective attention that refers to restricting attention to one or several elements of a stimulus or situation, while keeping the others out of attention.

  • Forebrain

    A broad term referring to a group of subcortical nuclei located roughly under the frontal lobes.

  • Frontal Lobe

    The frontal lobe is one of the four major subdivisions of cerebral cortex (others being temporal, parietal and occipital lobes). There are two of them, one in each hemisphere . Frontal lobes are involved in motor processing and executive functions . The frontal lobes contain the motor and premotor cortical areas as well as the prefrontal cortex.

  • Fronto-Temporal Dementia (FTD)

    A progressive neurodegenerative disease characterized by progressive atrophy in the temporal and frontal lobes of the brain. This can be accompanied by behavioral changes, difficulty in speech and impairment of complex cognitive activities like decision making. Fronto-Temporal Dementia (FTD) is distinguished from Alzheimer's disease by an earlier onset and personality changes that commonly occur with it, as opposed to the memory changes common in Alzheimer's disease.


  • Gamma-Aminobutyric Acid (GABA)

    A major neurotransmitter with mostly inhibitory properties.

  • Globus Pallidus

    The globus pallidus is part of the basal ganglia. It is primarily involved in voluntary movement.

  • Glutamate (GA)

    A major excitatory neurotransmitter of the brain.

  • Goal-directed behavior

    Behavior guided by a goal and free of distraction. The capacity for goal-directed behavior is linked to the functional integrity of the prefrontal cortex.

  • Goal-setting

    The cognitive process of creating a mental representation of what you want to accomplish, so that a plan can be generated to achieve it.


  • Handedness (Right or Left)

    The hand in an individual that has greater dexterity and finer motor skills. Most people are right-handed, but left-handedness is not uncommon. A small number of people are ambidextrous" and have equal ability in both hands. "

  • Healthy Aging

    Aging process characterized by the preservation of physical and mental abilities and general vitality.

  • Hemisphere

    One half of the brain, literally half of a sphere. It is important to distinguish between cerebral hemispheres and cerebellar hemispheres.

  • Hippocampus

    The name means seahorse memory consolidation. There are two hippocampi - one in each hemisphere.

  • Hypothalamus

    A subcortical structure consisting of a number of specific nuclei controlling eating and drinking behaviors, body temperature, certain aspects of reproductive behavior, and other functions.


  • Implicit Memory

    Memory that cannot be consciously recalled and communicated, but can be shown to exist without awareness through behavior and specific activities.

  • Impulse Control

    The ability to inhibit or defer an action or thought that is either inappropriate to the situation or will yield greater benefit at a later time. The best games to challenge impulse control are Ribbit Racers, Juice It, and Balloon Bust.

  • Insula

    The role of the insula is not well understood. It plays a role in multisensory integration, in dealing with emotions, and in other functions. It also has a role in the autonomic nervous system, regulating homeostasis.

  • Involuntary (Automatic) Attention

    The direction of one's attentional resources that is not under conscious control, usually toward a strong or unexpected sensory stimulus.

  • IQ

    IQ stands for Intelligence Quotient, which is a value calculated through the use of the Wechsler Intelligence Scale IV and purports to serve as a broadly based index of one's cognitive abilities. The use of WAIS IV IQ to characterize cognition is very common but it has been challenged on numerous grounds (e.g. as being culturally biased). It has also been acknowledged that no single variable can capture the totality of one's cognitive strengths and weaknesses, which gave rise to the notion of multiple intelligences, e.g. emotional intelligence.


  • Judgment

    The ability to assess various situations and challenges in a reasoned way. While it is impossible to localize judgment to any single part of the brain, the frontal lobes play a particularly important role in serving this function.


  • Language

    Language is an extremely versatile cognitive tool enabling us to represent various aspects of the world to formulate thought in a symbolic form and communicate complex ideas. Language is both a major accomplishment and a major driving force of human culture. Language is supported mostly by the cerebral cortex . In most adult individuals the left cerebral hemisphere is dominant in the neural control of language.

  • Language Dominant Hemisphere

    The cerebral hemisphere which controls most of the language functions (the left hemisphere in most people).

  • Lateralization

    Functional specialization as it relates to the two hemispheres of the brain. If certain cognitive, sensory or motor functions are controlled by a particular hemisphere (left or right) then that function is lateralized in that hemisphere.

  • Left Cerebral Hemisphere

    This hemisphere is mostly in charge of language and of "crystallized" cognitive skills. It receives sensory information from the right half of the sensory fields and controls the right side of the body.

  • Lewy Body Disease (LBD)

    A degenerative brain disorder characterized by gradually worsening cognitive impairment . LBD is a less prevalent type of dementia than Alzheimer's Disease (AD) and is characterized by a somewhat earlier onset. Unlike AD, it is not dominated by memory impairment and other aspects of cognition may be as or more impaired.

  • Lobe

    A major subdivision of cerebral cortex. Most classifications recognize four lobes: occipital , parietal , temporal , and frontal; but the insula is sometimes described as a fifth lobe. There are two of each lobe: one in the left hemisphere and the other one in the right hemisphere.


  • Memory

    The organism's ability to encode, store, and retrieve information. It is common to distinguish between verbal and nonverbal; visual, auditory, tactile and motor; explicit and implicit; declarative and procedural; and working memory . The best game to challenge memory is Match Maker.

  • Mental Flexibility

    The cognitive ability to switch between different cognitive tasks and activities without losing efficiency.The best game to challenge mental flexibility is Balloon Bust.

  • Motor Cortex

    The part of the frontal lobes in charge of communicating directly with subcortical structures in directing specific movements. Different parts of the motor cortex send commands to specific muscle groups.


  • Neocortex (Neocortical)

    The outer layer of the cerebral cortex , which supports higher-order cognitive functions such as perception, motor activity, spatial reasoning, language, decision making, and others. The Neocortex consists of six layers and is divided into four lobes : occipital , temporal , parietal, and frontal (one in each hemisphere).

  • Neuroimaging

    Techniques to reveal and visualize" the structure

  • Neuromodulators

    Neuromodulators and neurotransmitters are chemical substances which mediate communication between neurons. A distinction is sometimes made between neurotransmitters that act rapidly and locally, and "neuromodulators" that act more slowly and at a distance within the brain. But it is also common to refer to both as neurotransmitters.

  • Neuron

    A cell in the nervous system that communicates via both electrical and chemical signals. Neurons are the core component of the nervous system, including the brain, spinal cord, and peripheral nerves. Some neurons are specialized for processing sensory or motor information and activity, and others support higher-order functions like memory and decision making.

  • Neuroplasticity

    The capacity of the brain to change its function and structure in response to the environment. The effects of neuroplasticity can be targeted and directed by engaging the brain in specific activities. The extent of neuroplasticity is greater than used to be believed until a few decades ago. The more recent appreciation of the degree of neuroplasticity through the life span has been the basis for novel approaches to cognitive rehabilitation and enhancement.

  • Neuropsychiatry

    A clinical and research discipline concerned with the biological mechanisms of various psychiatric disorders, as well as their diagnosis and treatment.

  • Neuropsychology

    A clinical and research discipline concerned with the brain mechanisms of higher cognitive functions, with the diagnosis and treatment of cognitive impairment in various brain disorders.

  • Neurotransmitters

    Neurotransmitters and neuromodulators are chemical substances which mediate communication between neurons. A distinction is sometimes made between neurotransmitters" that act rapidly and locally

  • Non-Verbal Memory

    Memory for information delivered though means other than language . Non-verbal memory may be visuo-spatial, auditory, tactile, olfactory, or motor.The best games to challenge non-verbal memory are Match Maker and Shopkeeper.

  • Novel

    New or different from what was previously learned or experienced.


  • Obsessive-Compulsive Disorder (OCD)

    A disorder characterized by intrusive thoughts called obsessions and forced, repetitive behaviors called compulsions . OCD is often linked to impaired interaction between the striatum , prefrontal cortex and anterior cingulate cortex .

  • Occipital Lobe

    One of the four cortical lobes (the others are frontal , temporal and parietal ) located at the posterior of the brain and dedicated mainly to visual processing. There are two occipital lobes, one in each hemisphere .

  • Oxygen (O)

    Oxygen is a chemical element essential for the survival of a living organism. Of all the bodily structures, the brain is most oxygen-dependent.

  • Oxygen Deprivation

    A condition in which not enough oxygen is getting to the tissues and organs of the body. Because the brain is highly oxygen-dependent, it may particularly suffer from oxygen deprivation leading to hypoxia or anoxia. This may due to ischemic CVA , seizure, sleep apnea, or other causes such as drowning.


  • Parietal Lobe

    One of the four cortical lobes (the others being occipital, temporal and frontal) located towards the dorsal posterior aspect of the brain, beginning posterior to the central fissure. It is primarily concerned with the integration of tactile and proprioceptive information and also plays a role in higher-order functions, such as certain aspects of language, math, andspatial reasoning. There are two parietal lobes, one in each hemisphere.

  • Parkinson's Disease (PD)

    A disorder affecting the brain stem nuclei, Substantia Nigra (SN) and Ventral Tegmental Area (VTA), sending dopamine projections to other parts of the brain. PD is characterized by resting tremor and slowing of movement initiation. Higher-order cognitive impairments is also common.

  • Peripheral Nervous System

    This system connects the brain and spinal cord (the Central Nervous System ) to body's organs and limbs.

  • Phonology

    Differentiation of individual speech sounds from one another.

  • Planning (Executive)

    An aspect of executive functions in charge of identifying and aligning internal and external resources leading to the achievement of a goal. This requires anticipation and foresight, mental flexibility , as well as sustained effort and attention . Planning is among the functions primarily mediated by the prefrontal cortex .The best game to challenge planning is Packing Day.

  • Posterior

    Toward the back or back end.

  • Pragmatics

    Elements of language use that go beyond literal meaning. Pragmatics in language use is intertwined with judgment and appreciation of the context in which language is being used.

  • Prefrontal Cortex

    This area of the frontal lobes is most important for supporting executive functions , which include the ability to formulate goals and plans, and forcoordinating the activities of other parts of the brain necessary for coherent, goal-directed behavior.

  • Premotor Areas

    This area is part of the frontal lobe . It has diverse functions that relate to successfully executing and understanding complex motor behaviors.

  • Primary Sensory Cortical Projection Areas

    Regions of the neocortex that receive information in a particular sensory modality (visual, auditory or tactile) from subcortical structures.

  • Problem Solving

    The process of finding and implementing solutions to specific problems.The best games to challenge Problem Solving are Fruit 'n' Roll and Latin Squares.

  • Processing Speed

    Speed of mental operations. The existence of a single variable uniformly characterizing the speed of different types of mental operations in the same individual is controversial and has been challenged by some scientists.

  • Propositional Aspect of Language

    The ability to convey to others and to understand complex relationships (temporal, spatial, causal and others) communicated by means of language .

  • Prosody

    An element of language that conveys nuances of meaning through inflection, pitch, word stress, etc. This serves to enrich verbal communication and to convey contextual meaning, especially with regard to the emotional contents of language.

  • Putamen

    The putamen is part of the basal ganglia and is active in initiating and gating various behaviors. The putamen and the caudate nucleus are referred to as the striatum .



  • Schizophrenia

    A complex disorder characterized by a disturbance in thought processes as well as emotional responsiveness. Symptoms vary but they may include auditory hallucinations, delusions, disorganized speech or thought, as well as impairment of specificcognitive functions, particularly executive functions. Several types of this condition exist, so that it is increasingly common to talk about schizophrenias" rather than "schizophrenia.""

  • Seizures

    Seizures are the result of an abnormally large number of neurons firing excessively in synchrony. They may cause uncontrolled movement, loss of awareness, and alteration of mental state, among other symptoms. Seizures may be primary (idiopathic") traumatic brain injury or tumor), or cryptopathic" (when it is unclear if they are primary or secondary). Different types of seizures exist."

  • Selective Attention

    This is the element of attentionthat allows an individual to focus on a particular stimulus or stimuli while ignoring others in an environment. One example would be focusing on what a friend is saying to you across a loud and crowded room. The best games to challenge selective attention are Bag Snag and Shape Chef.

  • Social Intelligence

    A loosely used term referring to one's social skills and social judgment.

  • Stress

    Strain, pressure usually resulting from a prolonged exposure to unusual, highly demanding, or dangerous circumstances. Prolonged stress may cause brain atrophy, particularly in the hippocampi.

  • Striatum

    A group of subcortical brain structures that include the putamen and the caudate nucleus of thebasal ganglia,which gets its name from its "striped" or striated appearance. The striatum is involved in controlling motor behavior and also plays a role in executive functions in close coordination with theprefrontal cortex.

  • Stroke

    A colloquial synonym of Cerebrovascular Accident (CVA; see entry).

  • Subcortical Structures

    Structures in the brain which are located below thecerebral cortex.

  • Substantia Nigra

    This area is located in the brain stem and is highly concentrated with neurons that produce dopamine. It is involved in movement, reward, and addiction. Parkinson's disease affects this area.

  • Subthalamic Nuclei

    This area is considered by some to be part of the basal ganglia and is targeted in several treatments for Parkinson's disease.

  • Sustained Attention

    A mode of attention that involves maintaining attentional focus in a persistent manner over time. The best games to challenge sustained attention are Slalom Adventure, Supermarket Frenzy, Track and Field, and Vacation.

  • Symptom

    An observable manifestation of a disease.

  • Synapse

    The structure through which a neuron passes a signal to another neuron. This is typically accomplished through the release of chemical substances (neurotransmitters or neuromodulators ) which then cross a tiny space (the synaptic cleft) and bind to the receptors on a signal-receiving neuron.

  • Synaptic Vesicles

    Containment units that hold neurotransmitter or neuromodulator molecules and release them into the synaptic cleft following an action potential.

  • Syndrome

    A group of highly correlated symptoms which tend to appear together.


  • Temporal Lobe

    One of the four major cortical lobes (the others being frontal, parietal or occipital) located adjacently to the temples and posterior to the temples. This area of the brain is concerned with receiving and processing auditory information and plays a role in memory. It is also important in certain aspects of visual perception and in higher-order cognitive processes.

  • Thalamus

    This part of the brain relays sensory and motor information between the cerebral cortex and lower-level subcortical structures. It also plays a role in automatic attention and arousal. It consists of numerous nuclei divided into "specific" (conveying various types of sensory information) and "non-specific" (involved with various aspects of arousal).

  • The "What" System

    A pathway in the brain concerned with recognizing objects through visual inputs. This pathway starts in the primary visual cortex and proceeds ventrally toward the temporal lobes.In a healthy brain the "what" and "where" systems work closely together.

  • The "Where" System

    A pathway in the brain concerned with locating objects in space and where the viewer is in space in relation to these objects. This pathway starts in the primary visual cortex and proceeds dorsally toward the parietal cortex. In a healthy brain the "where" and "what" systems work closely together.

  • Tourette's Syndrome (TS)

    A disorder characterized by involuntary tics which can be motor or vocal, and frequently also by excessive exploratory behaviors. The disorder is thought to be caused by some dysfunction of the striatum and of its interaction with the prefrontal cortex.

  • Traumatic Brain Injury (TBI)

    Head injury that results in damage to the brain. Symptoms depend on the severity, type, and location of the damage and are highly variable. They may include alterations in concentration, memory, and thinking. Emotional and behavioral changes can also occur after TBI. Different types of TBI include closed (the most common), penetrating, and perforating.


  • Ventral

    Toward the front when referring to the spine and the brain stem; toward the bottom when referring to the cortex and the forebrain.

  • Verbal Memory

    Memory for the information communicated and received through means of language, spoken or written.

  • Visuospatial Functions

    Functions that engage or relate to perceiving the spatial relations between objects through the visual input.

  • Visuospatial Memory

    Memory for information received through the eye, such as memory for human faces, the shape of objects, and spatial layouts. The best games to challenge visuospatial memory are Face Ace and Shades & Shapes.

  • Voluntary Attention

    Attention which is directed internally through conscious effort and under conscious control. The best games to challenge voluntary attention are Bag Snag and Shape Chef.


  • Working Memory

    The memory system involved in selecting, temporarily storing and manipulating information necessary to successfully complete the cognitive task at hand. Tasks using working memory may require manipulating or monitoring information while resisting distractions or other competing processes. The dorsolateral prefrontal cortex plays a major role in supporting working memory. The term "working memory" has become somewhat of a fad and is sometimes used indiscriminately.